Proposed Pretreatment Standards for the 

Dental Category Include:

 Technology-based pretreatment standards for 

discharges of pollutants into POTWs from 

existing and new dental practices that involve 

the discharge of dental amalgam

 Dental offices covered by this proposed rule 

could control mercury discharges to POTWs 

by reducing their discharge of dental 

amalgam to a level achievable through the 

use of the best available technology 

(amalgam separators) and the use of Best 

Management Practices. 

 Amendments to selected parts of the General 

Pretreatment Regulations (40 CFR Part 403) 

to streamline oversight requirements for the 

dental sector and to eliminate discharge 

monitoring for the dentists.

Effluent Limitation Guidelines and Standards for the 

Dental Category

Summary

EPA is proposing technology-based 

pretreatment standards under the Clean Water 

Act for discharges of pollutants into publicly 

owned treatment works (POTWs) from existing 

and new dental practices that involve the 

discharge of dental amalgam. The proposal 

would require dental practices to comply with 

requirements for controlling the discharge of

dental amalgam pollutants into POTWs based on 

the best available technology or best available 

control technology and Best Management 

Practices. 

EPA is also proposing to amend selected parts of 

the General Pretreatment Regulations (40 CFR 

Part 403) to streamline oversight requirements 

for the dental sector. EPA expects compliance 

with this proposed rule would reduce the 

discharge of metals to POTWs by at least 8.8 

tons per year, half of which is mercury. EPA 

estimates the annual cost of the proposed rule

would be $44 to $49 million.

Why is EPA proposing this rule?

When dentists remove old amalgam fillings 

from cavities, or when dentists place a new 

filling, mercury in the form of dental amalgam 

enters the wastewater of the dental office. 

Studies have shown that dental offices are the 

largest source of mercury discharges to POTWs, 

contributing about half of the mercury received 

by POTWs. Mercury is a persistent and 

bioaccumulative pollutant with well-documented 

effects on human health. When in water, certain 

microorganisms can change mercury into 

methylmercury, a highly toxic form that builds 

up in fish, shellfish and animals that eat fish. 

Fish and shellfish are the main sources of 

methylmercury exposure to humans. 

The proposed rule would require all affected 

dentists to control mercury discharges to 

POTWs by reducing their discharge of dental 

amalgam to a level achievable through the use of 

the best available technology (amalgam

separators) and the use of Best Management 

Practices. In order to simplify compliance with, 

and enforcement of the numeric reduction 

requirements, the proposed rule would allow 

dentists to demonstrate compliance by installing, 

operating and maintaining amalgam separators. 

The proposal also includes a provision by which 

dental offices that have already installed 

amalgam separators that do not meet the 

proposed amalgam removal efficiency would 

still be considered in compliance with the rule

for the life of the amalgam separator. Removing 

concentrated sources of mercury to POTWs

opportunistically, such as through low-cost 

amalgam separators at dental offices (average 

annual cost per dental office: $700), is a 

common sense solution to managing mercury 

that would otherwise be released to air, land, and 

water.

Office of Water EPA - 821-F-14-002

www.epa.gov September 2014
For More Information

You can view the Federal Register Notice at

http://www.epa.gov/guide/dental. In addition, 

the proposed rule will be available at

http://www.regulations.gov under Docket ID: 

EPA-HQ-OW-2014-0693. Upon Federal 

Register publication, EPA will accept public 

comments on this proposed rule for 60 days.

You may also contact Damon Highsmith at 

Highsmith.Damon@epa.gov.